Hose assemblies are known in the art and such an assembly typically includes a hose constructed of rubber or similar material, a metal tube having a nipple portion which extends into one end of the hose, and a metallic shell. The shell surrounds a portion of the length of the hose at one end and clamps the hose to the nipple portion. The hose frequently takes the form of an extruded rubber (or synthetic rubber) inner core layer, a reinforcing layer of braided rayon, cotton or nylon or the like, and a covering or sheath of extruded rubber (or synthetic rubber).
Such hose assemblies have frequently been employed in automotive air conditioning systems which have been designed for carrying a refrigerant of the Freon type. More specifically, the refrigerant has included a type known as Freon 12 which does not corrode rubber. But it includes at least one chlorine molecule and is destructive to ozone molecules which may cause some depletion to the earth's ozone layer. To protect the ozone layer, recent legislation has proposed use of a Freon type refrigerant that does not include a chlorine molecule. Recently, a Freon refrigerant known as Freon HFC134a has been proposed. This refrigerant does not have a chlorine molecule and, hence, does not deplete the ozone layer. This refrigerant, however, is corrosive to rubber (including synthetic rubber). Consequently, there is a need to provide a protective layer on the inside surface of the hose to prevent contact between the rubber layer and the refrigerant. It has been determined that a thin protective layer taking the form of a plastic or nylon veneer will serve to provide adequate protection. A problem with such a thin plastic veneer is that it may be scratched by barbs extending radially outward from such a nipple. Depending upon the depth of such scratches, this may provide a location at which the refrigerant may escape and engage with the surrounding rubber layer, causing corrosion thereto. That might eventually lead to sufficient corrosion to result in leakage of the refrigerant to the surrounding atmosphere and thereby cause a breakdown in the proper operation of the associated air conditioning system.
In my U.S. Pat. No. 3,530,900, there is disclosed a hose assembly having barbs extending radially outward from the nipple portion. The barbs are illustrated as having an outer diameter corresponding with that of the outer diameter of the nipple portion and which, in turn, corresponds essentially with the inner diameter of the surrounding hose. If such a nipple were employed with a hose having a protective inner veneer as discussed above, the veneer may be scratched and damaged by the barbs.
In my U.S. Pat. No. 3,526,416 there is disclosed a hose assembly employing a nipple portion and two sets of axially spaced circumferential barbs. A first set is located closer to the free end of the nipple portion than the second set and is intended to be used with a reinforced hose having a plastic or nylon interior layer. The first set of barbs extend radially outward and have an outer diameter substantially greater than the inner diameter of the hose and are embedded into the inner layer thereof. In assembly, a clamp is installed so as to circumferentially surround the hose and provide clamping forces acting radially inward in the area of the first set of barbs. If the nipple portion of a hose assembly as described in my aforesaid U.S. Pat. No. 3,526,416 is employed with the newly proposed hose having an inner protective veneer, the barbs on that nipple portion may scratch and cause severe damage to the veneer which may lead to corrosion of the surrounding rubber layers with the consequent leakage problems as noted above.
In my U.S. Pat. No. 4,114,656, there is disclosed a hose assembly having a nipple which extends into the core of a hose and a loose shell which surrounds the end portion of the hose and the nipple to clamp the hose therebetween. The shell is referred to as a loose shell because it is not welded or otherwise secured to the tube or nipple to prevent relative axial movement therebetween. It is sometimes desired that such an assembly withstand tensile or axial forces and prevent relative axial movement between the nipple and the surrounding shell.